The inventor of the present invention has invented a surgical knife for cutting out a tendon sheath so as to treat for trigger fingers (see Japanese Patent Publishing Gazette No. 5-55136). A trigger finger means a finger, which cannot smoothly bend and stretch, and it is kept in a bending state when it is bent or stretched until reaching a prescribed angle; it springs back when it is further bent or stretched. Trissen fingers can be treated by cutting out tendon sheaths. The tendon sheath encloses a flexor tendon for bending and stretching a finger, so the damaged finger can be smoothly moved by cutting out the tendon sheath.
A conventional surgical knife is used for cutting out the tendon sheath, and it can be properly used for a normal skin incisional operation and a minimal skin incisional operation. FIG. 10 shows a side view of the conventional surgical knife for cutting out the tendon sheath; FIG. 11 shows an enlarged view of a blade section thereof. The surgical knife comprises: a grip section 10; a shaft section 12 being attached to the grip section 10; a blade section 14 being slightly extended from a side face of a front end section of the shaft section 12; and a guide section 16 being extended, in the same direction as the extended direction of the blade section 14, from a lower end of the blade section 14.
To use the surgical knife, as shown in FIG. 12, a front end of the guide section 16 is introduced into a space between a flexor tendon 18 and a tendon sheath 20, and the tendon sheath 20 is gradually cut out by sliding the guide section 16 on the flexor tendon 18. In the case of the minimal skin incisional operation, skin immediately above the tendon sheath is slightly cut to insert the blade section 14 of the surgical knife.